Toyota Repair: 1996 Toyota Corolla EGR Valve Problems, toyota corolla dx, egr valve

Question
Hi Ted,

I own a 1996 Toyota Corolla DX 1.8 with auto trans that has 150,000 miles on it. About 2 years agos the check engine light came on and I decided not to fix since the car ran fine with it on. At that time Autozone said the engine code indentifyer had something to do with EGR valve and that's all. I have kept up on all the oil changes and major service intervals since owning the car and it runs pretty darn well except the issue with the emissions.

Recently I decided I wanted to fix the problem so I had another diagnostic done by Autozone and it specifically said front O2 sensor problem, so I purchased a new one and installed myself. I also checked the filters in the Vacum Modulator and they were filthy so I replaced them with after market breather element cut to fit since Toyota won't sell just the filters.

Now the problem according to their diagnostic tool seems to say restricted air flow to EGR valve. Also I should mention after installing the O2 sensor, the car seem a little slugish and when accelerating slowly the car would bog or ping which would go away once I stepped harder on the gas.

I took off the EGR valve, the vacum modulator, and part of the throttle body and cleaned them out with cleaner and the check engine light is still on. Please advise I want to keep this car for another year or so. Thank you,

Dan Moore

Answer
Check the egr modulator again, there is a diaphragm inside that tends to break and leak through, remove the modulator and if you can blow air through the bottom pipe replace it, if that's not it let me know but it is by far the most common problem.
The o2 sensor may not be the correct one if the drivability problem started after the installation, check the engine timing, it should be at 8 degrees BTDC.